We have investigated regulation mechanism of fluid secretion from the salivary glands by calcium ions and cyclic AMP.1) Carbachol (CCh) and alpha-adrenergic action of noradrenaline induced secretion of polyanionic fluorescent dye, calcein, from isolated acinar cells. (2) Isoproterenorol (ISP) potentiated the CCh-induced release of calcein through beta-action. (3) CCh and alpha-adrenergic agonists increased the intracellular concentration of calcium ions. (4) Amylase secretion from isolated acinar cells was induced by beta-adrenergic agonists, but not CCh and alpha-adrenergic agonists. (5) The fluid secretion from perfused submandibular glands was induced by CCh and alpha-adrenergic agonists, but not by beta-adrenergic agonists. The secretion of calcein into the saliva was transiently induced by CCh and alpha-adrenergic agonists. (6) Calcium ionophore A23187 gradually increased the fluid secretion and transient calcein release. Removal of externalcalcium ions suppressed the late fluid secretion, but not calcein release. Addition of cyclic AMP rapidly suppressed the late fluid secretion. (7) K-Channel blocker Ba2+ inhibited the fluid secretion and calcein release. Cl-channel blocker DPC did not inhibit the calcein release, but suppressed the late fluid secretion. (8) Addition of CCh rapidly increased the luminal space and the secretion of calcein into intracellular apaces, and then induced vacuoles beneath the basolateral membranes. Removal of external calcium ions, Ba2+ and DPC suppressed the CCh-induced formation of vacuoles. (8)The phosphorylation of tyrosine-residues was observed in various proteins after CCh and ISP stimulation.